Electric circuit breaker



May 10, 1938. H. THOMMEN ELECTRIC CIRCUIT BREAKER Filed July :50, 1937 n www5,

Patented May 10, 1938 ELECTRIC CIRCUIT BREAKEB `Hans Thommen, Baden, Switzerland, assignor to Aktiengesellschaft Brown Boveri & Cie., Baden, lvvlilerland, a Joint-stock company of Switzer- App'umi; .my 3o, 1937, serial No. 156,554

190lalms.

This invention relates in general to circuit breakers, and more particularly to breakers of the iiuid blast type in which means are provided for inserting a resistor in the circuit to be opened by the breaker to thereby facilitate interruption of the arc therein.

It is well known to provide circuit breakers with contacts controlling the insertion of a resistor in the circuit to be opened by the breaker to reduce the current intensity in the arc and hence facilitate the interruption thereof. In circuit breakers of the fluid blast type, and particularly in circuit breakers of the gas blast type, it has been found that the size of the resistor may be considerably reduced and that the action of the gas blast in extinguishing the arc may be considerably improved by substituting an arrangement of coaxial contacts formed as solids of revolution in place of the usual rectangular contacts, and by utilizing a radial blast rather than a lateral blast for blowing out the arc. As an intermediate step in the operation of the breaker, the fluid blast causes transfer of the arc established between the arcing contacts from one of such contacts to an auxiliary contact coaxial therewith to introduce the resistor into the circuit. 'I'he fluid blast may also serve to dissipate the heat evolved in the resistor and the resistor may accordingly be placed in a discharge passage from the arcing chamber.

It is, therefore, one of the objects of the present invention to provide a circuit breaker of the uid lblast type in which a blast of fluid under pressure is utilized to transfer an arc from an arcing contact to an auxiliary contact for inserting .a resistor in the circuit controlled by the breaker.

, Another object of the present invention is to v.provide a circuit breaker oi the fluid blast type "inwhich an arc is transferred from one contact t to another contact coaxial therewith by means of a radial blast of fluid.

Another object of the present invention is to provide a circuit breaker of the fluid blast type in which a blast of fluid having served to transfer 50 an arc to a contact inserting a resistor in the circuit of the breaker is utilized for cooling the resistor.

Objects and advantages other than those above described will be apparent from the following description when read in connection with the accompanying drawing, in which:

Fig. 1 is a-view, in side elevation, of a circuit breaker embodying the features of the present invention; so Fig. 2 is a vertical cross section through the arc- July 30, 1936 (Cl. 20o-146) ing chamber of the circuit breaker illustrated in Fig. 1 taken on a plane parallel to the plane of projection utilized in Fig. 1;

Fig. 3 is a vertical cross s ection through a modiiied embodiment of the arcing chamber of the cir- 5 cuit breaker diiering from the embodiment i1- lustrated in Fig. 2 in the use of a fixed hollow auxiliary contact forming a discharge passage for the arcing chamber; and

Fig. 4 is a vertical cross section through a furl0 ther modified embodiment of the arcing chamber differing from the embodiment .illustrated in Fig. 3 in the use of a movable auxiliary contact.

Referring more particularly to the drawing by characters of reference, Fig. 1 illustrates a cir- 15 cuit breaker comprising as a constructive element thereof a reservoir 6 containing fluid under pressure. Such uid may be compressed air or any other suitable insulating fluid, but steam may also be used under certain operating conditions. 25 Reservoir 6 may be connected with the arcing chamber 1 of the circuit breaker through a hollow insulator 8 and through a suitable valve (not shown) which may be controlled by an overload relay 9 mounted on a projection III of the wall of 30 -chamber 1 forming one terminal of the breaker. Reservoir 6 also supports an insulator I I on which is mounted the pivot for the movable blade I2 of a disconnecting switch cooperating with the arcing contacts of the circuit breaker as will 35 appear hereinafter. Switch blade I2 may be actuated by any suitable mechanism such as a compressed uid motor I3 of the reciprocatory type connected therewith through a pair of connecting rods I4, a T-shaped crank I6 and a con- 40 necting rod I5 of insulating material. It will be understood that the elements of the circuit breaker may be duplicated and provided in suitable number when the breaker is to be used for controlling the iiow of 'current through a plurality 45 of conductors.

As shown in detail in Fig. 2, chamber 1 is of cylindrical form having a wall preferably made of conductive material provided with a circular port or orifice I1 coaxial with the bore of the 50 chamber.

'I'he lip of the wall of chamber 1 about orifice I1 may be provided with a flange to form an annular fixed contact I8 but it is generally preferred instead to arrange about the orice a 55 replaceable annular contact of suitable refractory conductive material such as tungsten. A tubular movable contact I9 is supported within chamber 1 and coaxially therewith by means of a piston 21 arranged for reciprocatory movement within a oo cylinder 22. Cylinder 22 is insulated from the wall of chamber 1 by a lining 23 which thus insulates contact I9 from contact I8 when such contacts are separated. Although contact I9 may be made in one piece it is generally preferred to provide such contact with a renewable arcing portion 24 adapted to engage contact I8 in abutting relation therewith and with another renewable arcing portion 2'6 to which the arc is to be transferred by a blast of i'luid under pressure. Contact portions 24 and 26 may also be made of refractory conductive material such as tungsten.

Contact I9 is generally maintained in abutting engagement with contact I8 by suitable resilient means such as a spring 21 acting between contact I8 and a diaphragm 28 closing the upper end of cylinder 22. Diaphragm 28 is provided with apertures for admitting fluid under pressure from chamber 1 into cylinder 22 to actuate piston 2| and contact 29 and thus separate contacts I9 and I8. The stroke of contact I9 is limited by abutment of the enlarged portion thereof against a cylinder 25 mounted on diaphragm 28 and also serving as guide for contact I9. Piston 2| is provided with suitable projections on which are fastened a pair of resilient contacts 29 adapted to engage switch blade I2 to form a disconnecting switch serially connected with arcing contacts I8 and I9. Piston 2| is also provided with an aperture arranged in alinement with the bore of contact I9 to form with such bore an auxiliary discharge passage for chamber 1.

Chamber 1 is provided with an inlet 3| through which fluid under pressure may be introduced to cause operation of piston 2|. Chamber 1 is also provided with a main discharge passage 32 communicating with the chamber through orice I1,

and the flow of fluid from chamber 1 into passage 32 may be given a whirling movement by means of helical vanes 33 arranged within the portion of chamber 1 adjacent contact I8. Passage 32 may be of cylindrical shape arranged to form an extension of chamber 1 and serves to confine the fluid blast projected from chamber 1 through orifice I1 upon separation of contacts I8 and I9. Passage 32 is preferably provided with a suitable structure for deionizing and cooling the fluid issuing from chamber 1, for separating therefrom metallic particles detached by the arc from the arcing contacts and for mufllng the report produced by the fluid blast. Such structure may consist of a sheet metal baille 34 wound to form a spiral convolute surface defining a spiral path issuing-fromgpassage 32 along a generatrix line of the wall thereof.

An auxiliary contact 36 is arranged outside of chamber 1 within passage 32 and extends into orifice I1 axially thereof. Contact 36 preferably protrudes into chamber 1 to an extent such that when contact I9 is removed from the position shown to the fully open position at a predetermined distance from contact I8, portion 26 of contact I9 is brought to a lesser distance from contact 36. Contact 36 is supported in position by Aa resistor 31 arranged outside of chamber 1 in passage 32 and fastened to the upper part of the wall of passage 32 in any suitable known manner such as by clamping. Contact 36 is connected through resistor 31 with one of the arcing contacts of the circuit breaker. 1n the embodiment illustrated in Fig. 2 such connection comprises the conductive wall of passage 32 and the wallof chamber 1, whereby contact 36 is connected with contact I8.

Resistor 31 may be made of any suitable known material such as silicon carbide and is chosen of the proper size to obtain the desired amount of resistance and to form a structure capable of carrying the required amount of current without undue heating. Resistor 31 is insulated from the space within passage 32 by means of a suitable insulation jacket 38.

The circuit breaker is inserted in the circuit to be controlled thereby by connecting one terminal of the circuit to the support of blade I2 and connecting the other terminal of the circuit with terminal I0 either directly or through a relay 9. When the circuit breaker is closed, the elements thereof are in the position shown in Figs. l and 2. When the circuit is to be opened by operation of the circuit breaker, a connection is established between reservoir 6 and insulator 8 either manually or by the action of relay 9 to admit fluid under pressure from reservoir 6 into insulator 8 and chamber 1. Orifice I1 then being closed by contacts I8 and I9, the pressure of the fluid within chamber 1 and within cylinder 22 rises to a value sufficient to cause downward movement of piston 2|. Piston 2| separates contact I9 from contact I8 and brings contact I9 into abutting engagement with the upper end of guide 25, and such operation causes an arc to be established between contact I8 and portion 24 of contact I9.

The connection between reservoir 6 and chamber 1 is maintained for a sufficient length of time to cause projection of a blast of iluid under pressure from chamber 1 through orifice I1 into passage 32 and between the convolutions of baille 34 to the ambient atmosphere while another uid blast is projected through the bore of hollow contact I9. When vanes 33 are provided, such vanes impart a whirling motion to such fluid blasts. The two fluid blasts jointly occupy the annular space contained between contacts I8, I9 and 36 wherein the fluid flows in a generally radial direction. The arc established between contacts I8 and I9 is thereby urged radially inward towards contacts 26 and 36, and the voltage drop in the arc is caused to increase by the lengthening thereof and by the deionizlng effect of the iluid blast. On the contrary, the gap between contacts 26 and 36, which is illled with fluid in a highly ionized condition, requires a gradually decreasing voltage for the establishment of an arc therein by dielectric breakdown.

When such voltage becomes lower than the voltage drop in the arc established between contacts I8 and I9, the arc is transferred from contact I8 to contact 3B. It will be understood, however, that when the circuit breaker is connected in an alternating current circuit, such transfer of the arc may take place during the first half cycle of arcing or else an apparent transfer of the arc may be eiected by extinction of the arc between contacts I8 and I9 during passage of the arc current through zero and subsequent ignition of another arc between contacts 26 and 36 at the beginning of the following half c cle.

yAfter such transfer the flow of current through the circuit breaker takes place from terminal I Il through the wall of passage 32, resistor 31, contact 36, contact 26, 24, I9, contact 29, and switch blade I2 to the other terminal of the circuit breaker. Resistor 31 causes the arc current flowing between contacts 26 and 36 to have a much.

the arc is readily extinguished by the blast of uid projected from chamber 1 through the bore of contact I9. It will be understood that the blast projected through contact I9 is of relatively low intensity compared to the blast projected through passage 32 and that therefore the fluid ionized and heated by the arc established between contacts 26 and 36, issues from contact I9 in a relatively cold and deionized condition. Such blast will accordingly not cause arcing over from contact 29 and switch blade I2 to chamber 1 or to other adjacent conductive members.

The insertion of the resistor in the circuit causes the latter to assume a generally resistive character with the result that any oscillation tending to be established therein by the exchange of energy between the inductive and capacitive portions thereof are damped, and hence the recovery voltage impressed across the contacts is limited to the voltage generated at the source supplying the circuit. In addition to the above actions, the space about contacts I8, I9 and 36 is swept by a blast of cold fluid in an un-ionized condition so that establishment of another arc between the contacts is prevented. Such fluid blast also serves to dissipate the heat produced in resistor 31 by the ow of current therethrough. After extinction of the arc, switch blade I2 may be disengaged from contact 29 by operation of motor I3 to insert, in the circuit, a gap of sufiicient length to permanently maintain the circuit open. 'I'he supply of fluid from reservoir 6 to chamber 1 may then be discontinued and contact I9 is returned to the position shown under the action of spring 21.

In the embodiment illustrated in Fig. 3, contact 36 is replaced by a tubular contact 39 mounted on a hollow resistor 4I. The circuit breaker may then be provided with a solid movable contact 42 instead of hollow contact I9. Contact 42 may, however, be provided with a hollow arcing portion 43 whereinto contact 39 may penetrate when contact 42 is in the closed position. In the present embodiment, when fluid under pressure is introduced into chamber 1 a part of the fluid blast projected through orifice I1 upon separation of contacts I8 and 42 is diverted through contact 39 `and resistor 4I for causing transfer of the arc from contact I3 to contact 39. The operation of the present embodiment is otherwise identical tov that of the embodiment illustrated in Fig. 2.

In the embodiment nlustrated in Fig. 4, thel xed auxiliary contact is replaced by a movable tubular auxiliary contact 44,slidable within insulator 38 and within resistor 4I. Contact 44 is adapted to engage a solid arcing portion 46 of contact 42 and is urged into engagement therewith by a spring 41. The movement of contact 44 is, however, limited by engagement of a flange 45 thereof with the lower portion of the wall of resistor 4|. Spring 41 may be arranged within resistor 4I and maintained in position therein by means of an insulation tube 48. Current is preferably transmitted between contact 44 and resistor 4I by means of a sliding contact 49 clamped on resistor 4I.

In the present embodiment, when fluid under 'pressure is admitted into chamber 1 contact 42 is urged downward as in the embodiment illustrated in Fig. 3. During the iirst part of the stroke of contact 42, contact 44 is maintained in engagement Vwith arcing portion 46 of contact 42 by spring 41. 'I'he flow of current between chamber 1 and contact 42 is then divided between two parallel paths. Part of such current ows from the wall of chamber 1 through contact I8 and therefrom to contact 42 through the arc established therebetween upon separation thereof. Another portion of such current flows from the wall of chamber 1 through the wall of passage 32, resistor 4I, contact 49, contact 44, and contact portion 46 to the body of contact 42. When contact 42 reaches a predetermined position, flange 45 engages the bottom of the wall of resistor 4| and causes contact 44 to stop. Contacts 44 and 42 accordingly separate and the arc established between contacts I8 and 42 is transferred by the iiuid blast from contact I8 to contact 44 which is in close proximity to arcing portion 46 of contact 42. The operation of the present embodiment is otherwise identical to that of the embodiment illustrated in Fig. 3.

Although but a few embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

l. An electric circuit breaker comprising an arcing chamber having an orifice, an annular fixedcontact arranged about said orifice, an auxiliary contact arranged outside of said chamber and extending into said orifice, a resistor arranged outside of said chamber and connecting said fixed contact with said auxiliary contact, a movable Contact arranged within said chamber, and means for actuating said movable contact.

2. An electric circuit breaker comprising an arcing chamber having an orifice, a discharge passage for said chamber communicating therewith through said orifice, an annular xed contact arranged about said orifice, an auxiliary contact arranged within said passage, a movable contact arranged within said chamber, a resistor arranged outside of said chamber and connecting said auxiliary contact with another one of said contacts, and means for actuating said movable contact.

3. An electric circuit breaker comprising an arcing chamber having an orifice, a discharge passage for said chamber communicating therewith through said orifice, an annular'fixed contact arranged about said orifice, an auxiliary contact arranged within said passage, a movable contact arranged within said chamber, a resistor arranged outside of said chamber and connecting said auxiliary contact with another one of said-contacts, means for actuating said movable contact, and means fo'r projecting a blast of fluid under pressure from said chamber through said orifice upon separation of said fixed and movable contacts.

4. An electric circuit breaker comprising an arcing chamber having an orifice, a discharge passage for said chamber communicating there- 'with through said orifice, an annular fixed contact arranged about said orifice, an auxiliary contact arranged within said passage, a movable contact arranged within said chamber, a resistor arranged outside of said chamber and connecting said auxiliary contact with another one of said contacts, means for actuating said movable contact, means for projecting a blast of fluid under pressure from said chamber through said orifice upon separation of said fixed and movable contacts, and means for imparting a whirling motion to said fluid blast through said orifice.

5. An electric circuit breaker comprising an arcing chamber having an orifice, a discharge passage for said chamber communicating therewith through said orifice, an annular fixed contact arranged about said orifice, an auxiliary Contact arranged within said passage, a movable contact arranged within said chamber, one of said auxiliary and movable contacts being hollow and forming a second discharge passage for said chamber, a resistor arranged outside of said chamber and connecting said auxiliary contact with one of said xed and movable contacts, means for actuating said movable contact, and means for projecting a blast of fluid under pressure from said chamber through said passages upon separation of said nxed and movable contacts.

6. An electric circuit breaker comprising an arcing chamber having an orice, a discharge passage for said chamber communicating therewith i.irough said orifice, an annular fixed contact arranged about said orifice, an auxiliary contact arranged within sai-d passage, a movable contact arranged within said chamber, a resistor arranged outside of said chamber and connecting said auxiliary contact with another one of said contacts, means for separating said fixed and movable contacts to thereby establish an arc therebetween, and means for projecting a blast of fluid under pressure from said chamber through sai-d orifice upon separation of said fixed and movable contacts to transfer the are established therebetween from said another one of said contacts to said auxiliary contact.

7. An electric circuit breaker comprising an arcing chamber having an orifice, an annular nxed contact arranged about said orifice, an auxiliary contact arranged outside of said chamber and extending into said orice, a resistor arranged outside of said chamber and connecting said fixed contact with said auxiliary contact, a movable contact arranged within said chamber, means for actuating said movable contact, and means for projecting a blast of fluid under pressure from said chamber through said orice upon separation of said fixed and movable contacts.

8. An electric circuit breaker comprising an arcing chamber having an orice, an annular xed contact arranged about said orifice, an auxiliary contact arranged outside of said chamber and extending into said orifice, a resistor arranged outside of said chamber and connecting 'said fixed contact with said auxiliary contact, a

movable contact arranged within said chamber, one of said auxiliary and movable contacts being hollow, means for separating said fixed and movable contacts, and means for projecting ablast of fluid under pressure from said chamber through said orifice and through said hollow contact upon separation of said fixed and movable contacts.

9. An electric circuit breaker comprising an arcing chamber having an orifice, an annular I pressure from said chamber through said orifice upon separation of said fixed and movable contacts to transfer the arc established therebetween from said fixed contact to said auxiliary contact.

10. An electric circuit breaker comprising an arcing chamber having an orifice, an annular fixed contact arranged about said orifice, an auxiliary contact arranged outside of said chamber and extending into said orifice, a resistor arranged outside of said chamber and connecting said fixed contact with said auxiliary contact, a movable contact arranged within said chamber in contacting engagement with said fixed contact, means for actuating said movable contact whereby said movable contact is removed to a predetermineddistance from said fixed contact and to a lesser distance from said auxiliary contact, and means for projecting a blast of fluid under pressure from said chamber through said orifice upon separation of said fixed and movable contacts to transfer the arc established therebetween from said xed contact to said auxiliary contact.

ll. Ari electric circuit breaker comprising an arcing chamber having an orifice, an annular fixed contact arranged about said orice, an auxiliary contact arranged outside of said chamber and extending into said orice, a resistor arranged outside of said chamber and connecting said xed contact with said auxiliary contact, a tubular movable contact arranged within said chamber, means for separating said fixed and movable contacts, and means for projecting a blast of fluid under pressure from said chamber through said orifice and through said movable contact upon separation of said fixed and movable contacts.

l2. An electric circuit breaker comprising an arcing chamber having an orifice, an annular fixed contact arranged about said orifice, a tubular auxiliary contact arranged outside of said chamber and extending into said orifice, a resistor arranged outside of said chamber and connecting said fixed contact with said auxiliary contact, a movable contact arranged within said chamber, means for separating said fixed and movable contacts, and means for projecting a blast of fluid under pressure from said chamber through said orifice and through said auxiliary contact upon separation of said fixed and movable contacts.

13. An electric circuit breaker comprising an arcing chamber having an orifice, an annular fixed contact arranged about said orifice, a movable contact arranged within said chamber in contacting engagement with said fixed contact, an auxiliary contact arranged outside of said chamber and extending into said orifice, a resistor arranged outside of said chamber and connecting said fixed contact with said auxiliary contact, means for urging said auxiliary contact into engagement with said movable contact, means for .limiting the movement of said auxiliary contact, -means for actuating said movable contact whereby said movable contact is removed to a predetermined distance from said fixed contact and to a lesser distance from said auxiliary contact, and means for projecting a blast of fluid under pressure from said chamber through sai-d orifice upon separation of said fixed and movable contacts .to transfer the arc established therebetween from said fixed contact to said auxiliary contact.

14. An electric circuit breaker comprising an arcing chamber having an orifice, a discharge passage for said chamber communicating therewith through said orifice, an annular xed contact arranged about said orifice, an auxiliary contact arranged within said passage, a movable contact arranged within said chamber, a resistor arranged within said passage and connecting said auxiliary contact with another one of said contacts, means for actuating said movable contact, and means for projecting a blast of fluid under pressure from said chamber into said passage upon separation of said fixed and movable contacts.

15. An electric circuit breaker comprising an arcing chamber having an orifice, a discharge passage for said chamber communicating therewith through said orice, an annular fixed contact arranged about said orifice, an auxiliary contact arranged within said passage, a movable contact arranged within said chamber, a resistor arranged within said passage and connecting said auxiliary contact with said fixed contact, means for actuating said movable contact, and means for projecting a blast of fluid under pressure from said chamber into said passage upon separation of said fixed and movable contacts.

16. An electric circuit breaker comprising an arcing chamber having an orifice, an annular fixed contact arranged about said orifice, an auxiliary contact arranged outside of said chamber and extending into said orifice, a resistor arranged outside of said chamber and connecting said fixed contact with said auxiliary contact, a movable Acontact arranged within said chamber, means operable by fiuid under pressure within said chamber for separating said fixed and movable contacts, and means for introducing fiuid under pressure into said chamber to cause operation of said contact separating means and to cause fluid under pressure to be projected from said chamber through said orifice.

17. An electric circuit breaker comprising an arcing chamber having an orifice, a discharge passage for said chamber communicating therewith through said orifice, an annular fixed contact arranged about said orifice, an auxiliary conarcing chamber having an orifice, a discharge v passage for said chamber communicating therewith through said orifice, an annular fixed contact arranged about said orifice, an auxiliary contact arranged within said passage, a movable contact arranged within said chamber, a resistor arranged within said passage and connecting said auxiliary contact with another one of said contacts, means operable by fluid under pressure within said chamber for separating saidfixed and movable contacts, and means for introducing iiuid under pressure into said chamber to cause operation of said contact separating means and to cause fluid under pressure to be projected from said chamber through said orifice.

19. An electric circuit breaker comprising an arcing chamber having an orifice, a discharge passage fqr said chamber communicating therewith through said orifice, an annular fixed contact arranged about said orifice, an auxiliary contact arranged within said passage, a movable contact arranged within said chamber, a resistor arranged within said passage and connecting said auxiliary contact with said fixed contact, means operable by fluid under pressure within said chamber for separating said fixed and movable contacts, and means for introducing fiuid under pressure into said chamber to cause operation of said contact separating means and to cause fluid under pressure to be projected from said chamber through said orifice.

HANS THOMMEN. 

